State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China, College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China and Synergetic Innovation Center of Chemical Science and Engineering, 94 Weijin Road, Tianjin 300071, China.
Nucleic Acids Res. 2013 Dec;41(22):10619-29. doi: 10.1093/nar/gkt819. Epub 2013 Sep 14.
The highly conserved Paf1 complex (PAF1C) plays critical roles in RNA polymerase II transcription elongation and in the regulation of histone modifications. It has also been implicated in other diverse cellular activities, including posttranscriptional events, embryonic development and cell survival and maintenance of embryonic stem cell identity. Here, we report the structure of the human Paf1/Leo1 subcomplex within PAF1C. The overall structure reveals that the Paf1 and Leo1 subunits form a tightly associated heterodimer through antiparallel beta-sheet interactions. Detailed biochemical experiments indicate that Leo1 binds to PAF1C through Paf1 and that the Ctr9 subunit is the key scaffold protein in assembling PAF1C. Furthermore, we show that the Paf1/Leo1 heterodimer is necessary for its binding to histone H3, the histone octamer, and nucleosome in vitro. Our results shed light on the PAF1C assembly process and substrate recognition during various PAF1C-coordinated histone modifications.
高度保守的 Paf1 复合物 (PAF1C) 在 RNA 聚合酶 II 转录延伸和组蛋白修饰的调节中发挥关键作用。它还与其他多种细胞活动有关，包括转录后事件、胚胎发育以及细胞存活和胚胎干细胞特性的维持。在这里，我们报告了 PAF1C 内的人 Paf1/Leo1 亚基复合物的结构。整体结构表明，Paf1 和 Leo1 亚基通过反平行 β-折叠相互作用形成紧密相关的异二聚体。详细的生化实验表明，Leo1 通过 Paf1 结合 PAF1C，并且 Ctr9 亚基是组装 PAF1C 的关键支架蛋白。此外，我们表明 Paf1/Leo1 异二聚体对于其与组蛋白 H3、组蛋白八聚体和核小体的体外结合是必需的。我们的结果阐明了 PAF1C 组装过程和在各种 PAF1C 协调的组蛋白修饰过程中的底物识别。
